aging - highlighted topics J Appl Physiol 95: 17171727,...

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highlighted topics Physiology of Aging Invited Review: Aging and sarcopenia Timothy J. Doherty Department of Physical Medicine and Rehabilitation and The Canadian Centre for Activity and Aging, The Lawson Health Research Institute and St. Joseph’s Health Centre, The University of Western Ontario, London, Ontario, Canada N6A 1Y6 Doherty, Timothy J. Invited Review: Aging and sarcopenia. J Appl Physiol 95: 1717–1727, 2003;10.1152/japplphysiol.00347.2003.—Aging is associated with progressive loss of neuromuscular function that often leads to progressive disability and loss of independence. The term sar- copenia is now commonly used to describe the loss of skeletal muscle mass and strength that occurs in concert with biological aging. By the seventh and eighth decade of life, maximal voluntary contractile strength is decreased, on average, by 20–40% for both men and women in proximal and distal muscles. Although age-associated decreases in strength per unit muscle mass, or muscle quality, may play a role, the majority of strength loss can be accounted for by decreased muscle mass. Multiple factors lead to the development of sarcopenia and the associated impact on function. Loss of skeletal muscle Fbers secondary to decreased numbers of motoneurons appears to be a major contributing in±uence, but other factors, including decreased physical activity, altered hormonal status, decreased total caloric and protein intake, in±ammatory media- tors, and factors leading to altered protein synthesis, must also be considered. The prevalence of sarcopenia, which may be as high as 30% for those $ 60 yr, will increase as the percentage of the very old continues to grow in our populations. The link between sarcopenia and disability among elderly men and women highlights the need for continued re- search into the development of the most effective interventions to pre- vent or at least partially reverse sarcopenia, including the role of resis- tance exercise and other novel pharmacological and nutritional interven- tions. skeletal muscle; muscular strength; muscle quality; motoneuron; coun- termeasures; muscle protein IT IS WELL ESTABLISHED THAT the human aging process, from maturity to senescence, is associated with a sig- niFcant decline in neuromuscular function and perfor- mance (34, 51, 109, 128). Characteristic of this decline is the inevitable reduction in skeletal muscle mass and associated loss of strength that occurs even in the healthy elderly. Rosenberg (110) Frst coined the term Sarcopenia , from the Greek, which literally means poverty of ±esh, to describe age-associated loss of skel- etal muscle mass. Sarcopenia is now generally used to describe age-related changes that occur within skeletal muscle and thus encompasses the effects of altered central and peripheral nervous system innervation, altered hormonal status, in±ammatory effects, and al- tered caloric and protein intake. These multiple factors all contribute to sarcopenia and to the characteristic skeletal muscle atrophy and weakness, both of which
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aging - highlighted topics J Appl Physiol 95: 17171727,...

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